protocol

package
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 Go to latest Published: Sep 10, 2017 License: AGPL-3.0 Imports: 13 Imported by: 0

Documentation

Overview

Package protocol provides the logic to tie together storage and validation for a Chain Protocol blockchain.

This comprises all behavior that's common to every full node, as well as other functions that need to operate on the blockchain state.

Here are a few examples of typical full node types.

Generator

A generator has two basic jobs: collecting transactions from other nodes and putting them into blocks.

To add a new block to the blockchain, call GenerateBlock, sign the block (possibly collecting signatures from other parties), and call CommitBlock.

Signer

A signer validates blocks generated by the Generator and signs at most one block at each height.

Participant

A participant node in a network may select outputs for spending and compose transactions.

To publish a new transaction, prepare your transaction (select outputs, and compose and sign the tx) and send the transaction to the network's generator. To wait for confirmation, call BlockWaiter on successive block heights and inspect the blockchain state until you find that the transaction has been either confirmed or rejected. Note that transactions may be malleable if there's no commitment to TXSIGHASH.

To ingest a block, call ValidateBlock and CommitBlock.

Index

Constants

This section is empty.

Variables

View Source 
var (
	// ErrBadBlock is returned when a block is invalid.
	ErrBadBlock = errors.New("invalid block")

	// ErrStaleState is returned when the Chain does not have a current
	// blockchain state.
	ErrStaleState = errors.New("stale blockchain state")

	// ErrBadStateRoot is returned when the computed assets merkle root
	// disagrees with the one declared in a block header.
	ErrBadStateRoot = errors.New("invalid state merkle root")
)
View Source 
var ErrBadTx = errors.New("invalid transaction")

ErrBadTx is returned for transactions failing validation

View Source 
var (
	// ErrTheDistantFuture is returned when waiting for a blockheight
	// too far in excess of the tip of the blockchain.
	ErrTheDistantFuture = errors.New("block height too far in future")
)

Functions

func NewInitialBlock 

func NewInitialBlock(pubkeys []ed25519.PublicKey, nSigs int, timestamp uint64) (*legacy.Block, error)

Types

type Chain 

type Chain struct {
	InitialBlockHash  bc.Hash
	MaxIssuanceWindow time.Duration // only used by generators
	// contains filtered or unexported fields
}

Chain provides a complete, minimal blockchain database. It delegates the underlying storage to other objects, and uses validation logic from package validation to decide what objects can be safely stored.

func NewChain 

func NewChain(ctx context.Context, initialBlockHash bc.Hash, store Store, heights <-chan uint64) (*Chain, error)

NewChain returns a new Chain using store as the underlying storage.

func (*Chain) ApplyValidBlock 

func (c *Chain) ApplyValidBlock(block *legacy.Block) (*state.Snapshot, error)

ApplyValidBlock creates an updated snapshot without validating the block.

func (*Chain) BlockSoonWaiter 

func (c *Chain) BlockSoonWaiter(ctx context.Context, height uint64) <-chan error

BlockSoonWaiter returns a channel that waits for the block at the given height, but it is an error to wait for a block far in the future. WaitForBlockSoon will timeout if the context times out. To wait unconditionally, the caller should use WaitForBlock.

func (*Chain) BlockWaiter 

func (c *Chain) BlockWaiter(height uint64) <-chan struct{}

BlockWaiter returns a channel that waits for the block at the given height.

func (*Chain) CommitAppliedBlock 

func (c *Chain) CommitAppliedBlock(ctx context.Context, block *legacy.Block, snapshot *state.Snapshot) error

CommitBlock commits a block to the blockchain. The block must already have been applied with ApplyValidBlock or ApplyNewBlock, which will have produced the new snapshot that's required here.

This function saves the block to the store and sometimes (not more often than saveSnapshotFrequency) saves the state tree to the store. New-block callbacks (via asynchronous block-processor pins) are triggered.

TODO(bobg): rename to CommitAppliedBlock for clarity (deferred from https://github.com/chain/chain/pull/788)

func (*Chain) GenerateBlock 

func (c *Chain) GenerateBlock(ctx context.Context, prev *legacy.Block, snapshot *state.Snapshot, now uint64, txs []*legacy.Tx) (*legacy.Block, *state.Snapshot, error)

GenerateBlock generates a valid, but unsigned, candidate block from the current pending transaction pool. It returns the new block and a snapshot of what the state snapshot is if the block is applied.

After generating the block, the pending transaction pool will be empty.

func (*Chain) GetBlock 

func (c *Chain) GetBlock(ctx context.Context, height uint64) (*legacy.Block, error)

GetBlock returns the block at the given height, if there is one, otherwise it returns an error.

func (*Chain) Height 

func (c *Chain) Height() uint64

Height returns the current height of the blockchain.

func (*Chain) Recover 

func (c *Chain) Recover(ctx context.Context) (*legacy.Block, *state.Snapshot, error)

Recover performs crash recovery, restoring the blockchain to a complete state. It returns the latest confirmed block and the corresponding state snapshot.

If the blockchain is empty (missing initial block), this function returns a nil block and an empty snapshot.

func (*Chain) State 

func (c *Chain) State() (*legacy.Block, *state.Snapshot)

State returns the most recent state available. It will not be current unless the current process is the leader. Callers should examine the returned block header's height if they need to verify the current state.

func (*Chain) ValidateBlock 

func (c *Chain) ValidateBlock(block, prev *legacy.Block) error

ValidateBlock validates an incoming block in advance of applying it to a snapshot (with ApplyValidBlock) and committing it to the blockchain (with CommitAppliedBlock).

func (*Chain) ValidateBlockForSig 

func (c *Chain) ValidateBlockForSig(ctx context.Context, block *legacy.Block) error

ValidateBlockForSig performs validation on an incoming _unsigned_ block in preparation for signing it. By definition it does not execute the consensus program.

func (*Chain) ValidateTx 

func (c *Chain) ValidateTx(tx *bc.Tx) error

ValidateTx validates the given transaction. A cache holds per-transaction validation results and is consulted before performing full validation.

type Store 

type Store interface {
	Height(context.Context) (uint64, error)
	GetBlock(context.Context, uint64) (*legacy.Block, error)
	LatestSnapshot(context.Context) (*state.Snapshot, uint64, error)

	SaveBlock(context.Context, *legacy.Block) error
	FinalizeBlock(context.Context, uint64) error
	SaveSnapshot(context.Context, uint64, *state.Snapshot) error
}

Store provides storage for blockchain data: blocks and state tree snapshots.

Note, this is different from a state snapshot. A state snapshot provides access to the state at a given point in time -- outputs and issuance memory. The Chain type uses Store to load state from storage and persist validated data.

Source Files

View all Source files

Directories

Path Synopsis
bc
Package bc is a generated protocol buffer package.
 Package bc is a generated protocol buffer package.
bctest
Package bctest provides utilities for constructing blockchain data structures.
 Package bctest provides utilities for constructing blockchain data structures.
legacy
Package patricia computes the Merkle Patricia Tree Hash of a set of bit strings, as described in the Chain Protocol spec.
 Package patricia computes the Merkle Patricia Tree Hash of a set of bit strings, as described in the Chain Protocol spec.
Package prottest provides utilities for Chain Protocol testing.
 Package prottest provides utilities for Chain Protocol testing.
memstore
MemStore is a Store implementation that keeps all blockchain state in memory.
 MemStore is a Store implementation that keeps all blockchain state in memory.
Package vm implements the VM described in Chain Protocol 1.
 Package vm implements the VM described in Chain Protocol 1.

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